WeldForming: a new inline process combination to improve weld seam properties

Abstract

The high heat input during fusion welding leads to transformations of the microstructure in the area subjected to welding, mostly resulting in a heterogene crystalline structure and an overall deterioration of the mechanical properties. To reduce the detrimental effect, posttreatment processes which are typically separated from the actual welding process are state of the art. The present work shows the new methodology, WeldForming, which intends to eliminate subsequent treatment processes. The new in-line process combination harnesses the synergies of a welding and a rolling process to ultimately prevent the typical zone formation of the heat affected zone. Experimental investigations combined with a detailed numerical simulation of the coupled welding and forming process indicate the functional proof of the new methodology. The validation of the numerical model is carried out with the aid of temperature profiles, cross sections, and microstructure analysis as well as flow curves determined by upsetting tests on thermomechanical simulation systems.

The Benefit of the Process Combination of Wire Arc Additive Manufacturing (WAAM) and Forming—A Numerical and Experimental Study

“…The first strategy (Figure 2a) includes the process combination of welding and forming a single layer single-bead. This process was examined in [8] and the obtained experimental data was used to develop and validate a simulation model for the simple process combination. The simulation model was calibrated by thermal measurements with thermo couples regarding cooling during welding and forming.…”

“…However, this is preliminary work and the results indicate further machining procedures are required. A study by Adams et al on the inline WeldForming process exhibits validation of the numerical model followed by microstructural analysis [8].…”

“…Figure 2. Considered process combinations, (a) 1st strategy-process with hot rolling for development and validation of a simulation model with experimental data (Reprinted from Ref [8]…”

The effect of thermomechanical welding on the microstructure and mechanical properties of S700MC steel welds

“…Reducing the ratio increases the weld joint's strength during tensile tests. According to many researches [ 13 – 16 ], the degree and extent of softening in part of the HAZ are mostly related to the base material, the cooling time t 8/5 [s], and thus the welding procedures [ 23 – 26 ]. The width of the HAZ soft zone expands linearly with an increase in the t 8/5 [ 17 – 21 ].…”

“…Grain refinement is an important method to improve the mechanical properties of a TIG weld. The single plastic deformation through the WeldForming process was used by Adams et al [ 26 ] to improve the weld seam properties of HSSs. Our previous work [ 27 ] demonstrated that the plastic deformation combined with frequent vibrations during thermomechanical welding (TMW) can refine the microstructure of the FZ by occurring recrystallisation processes.…”